Some would probably say: “what kind of a question is that?! You just find a calorie calculator in the Internet, fill in some basic data and there’s the answer”. So maybe the question should be rephrased as: How do THEY know how many calories there is in food? And by “them” I mean nutritionists and the people who have developed the calorie calculators. Many of us count calories, but do we really know what the calories are?
Calories vs. calories
It all comes down to physics, actually. We used to talk, write and read about calories, which in terms of physics, are very small units of energy. In fact, talking about calories in food, we usually mean kilocalories (a.k.a. kcal or Calories). Here’s the difference between the two:
- 1 calorie is the amount of energy needed to heat 1 gram of water to 1 Celsius degree
- 1 Calorie (kilocalorie, or kcal) is the amount of energy needed to heat 1 kilogram of water to 1 Celsius degree
Thus, 1 calorie is 1/1000 of a Calorie
The estimates given in calorie calculator are given in Calories (kcal), even if they say “calories”.
How does the process of measuring calories in food looks like?
To measure the amount of calories included in piece of food, the scientist use a piece of lab equipment called the bomb calorimeter. The bomb calorimeter is constructed of two chambers, one put inside of the other. They put a piece of food (of a certain mass) in the inner chamber.
Next, the chamber is filled up with oxygen and tightly locked. The outer chamber is filled with the measured amount of water. An electric spark ignites the food in oxygen – the food is literally burned. What is actually measured is the change of water temperature.
Basically, if the water gets warmer of 1 Celsius degree per kilogram, it means the food has 1 kcal. And if the temperature rises of 70 degrees per kilogram of water, the food has 70 kcal.
Does it mean the food producers burn food in the lab?
Probably, hardly any of them does. They estimate the calories on the basis of how much carbohydrates, protein and fat their product includes.
- 1 gram of carbohydrates is estimated as 4 kcal
- 1 gram of protein is estimated as 4 kcal
- 1 gram of fat is estimated as 9 kcal
What’s important, the estimation of calories used on food labels considers the fact that human body cannot “burn” all of the food we’re eating, as it takes place in the bomb calorimeter. For more details, see the movie below broadcasted by GUStrength.
Do we really need to count the calories?
As you can see, the numbers are just estimation rather than complete data. They do give us a sense of control over what we eat. But healthy eating isn’t just about the amount of calories. For instance, a wheatmeal biscuit and an apple are both 70 kcal. Both include carbohydrates and sugar. An apple, however, contains natural fructose, vitamins, amino acids, and fiber. The biscuit, on the other hand, is made of white flour, refined sugar, oil, and salt.
So it’s not only about how much energy we provide your body with, but in what ingredients the energy is actually contained. Also, we can estimate, on the basis of a table from the internet or a smartphone app, that a piece of meat we’re going to eat for dinner is X kcal. But actually, we’re not sure what percentage of the piece of meat is fat, and what percentage is protein. We estimate all the time.
All in all, the scrupulous counting of every calorie is not what we need to lose weight. The counting itself does not make us burn fat. We really do not have to count calories to know that it’s more beneficial for us to eat a piece of fruit instead of a cookie. But if you really need counting calories, and that’s what makes you happy, you should at least be aware of what you’re actually counting.
Counting or not, be reasonable and don’t let the numbers take control over your mind.